Intro

We've asked Francois Simond (supercurio), creator of the very popular project-voodoo and voodoo-sound improvement packages, and Android hacker focused on sound, video, and image, to set the record straight on Samsung Galaxy S 2's sound quality. In addition, Francois will help us test smartphone and mobile-device sound quality and continue being a contributor as it quickly becomes an important industry focus.

Context

Galaxy S II comes with a lot of expectations in the audio department. Samsung’s previous flagship family, Galaxy S, (aka Vibrant, Captivate, Fascinate, Galaxy S 4G, Epic 4G in the US) set the bar high, using a good quality implementation of Wolfson Micro WM8994 codec. Existing custom mods which tuned WM8994 usage have even been able to push the quality higher than most expected, as well as the headphone output levels.

Yamaha YMU823 - Encircled in Red Above

For the Galaxy S II, however, Samsung changed audio IC suppliers, preferring the popular Japanese brand Yamaha making a big entry in the the low power codec for Smartphones area. The exact chip used in Galaxy S II devices is named C1-YMU823 (also refereed as MC-1N2).

Its datasheet is not public but it’s a chip designed designed to compete with latest Wolfson and TI offerings and probably a custom product designed to follow Samsung requirements.

As the growing interest of readers and recent HTC and Beats by Dre strategic alliance shows, smartphone audio capabilities constantly gain importance. Of course, solid voice call performance remains a major concern. Many smartphone owners now use their device as a primary music player, sometimes with high-end headphones.

Audio Performance

Music

Demanding enthusiasts expected As music player Galaxy S II to sound at least as good as its Apple competitor: iPhone 4 and supersede its older brother Galaxy S performance.

Unfortunately, it fails at both.

As music player, Galaxy S II performance can be described as:

Average for a smartphone.

Below average for a high end smartphone.

Yamaha’s MC-1N2 codec has some nice theoretical specs, but the promised sound fidelity turns into a boring rendering affected by several outstanding issues, relegating Samsung flagship far from the audiophile category. Worse: only some of those issues can be remedied by using additional equipment like an attenuator or an active headphone amplifier.

Galaxy S II audio output as music player has issues

Audible CPU and Radio noise

Today most listeners enjoy music with isolating earphones, as they are useful for listening to music or podcasts in loud environments without having to pump the volume up and introduce listening fatigue. Most in-ear gear is highly sensitive. Combined with low impedance and 20dB isolation, hiss and other noise are quickly noticeable.

Due to its bursty nature, this flaw is hard to expose in measurements and fortunately less audible with medium sensitivity headphones, not at all with low sensitivity ones.

You can solve this issue by using an attenuator or amplifier: maximizing digital Android output level and adjusting the volume to your need with the amp.

DAC Distortion

With today’s Android audio implementation, all kind of media are sent to the DAC as a 44100 / 16bit / Stereo stream. Despite the usage of a fixed rate, Yamaha’s codec is not able to provide a very clean output.

Galaxy S II DAC output quality is limited by several kind of distortions. So far, no firmware was able to fix those despite early Korean updates describing “audio clarity improvements”.

When playing music, those artifacts are perceived as “lack of clarity”, “reduction of stereo separation”, “loss of detail” and “lifeless sound” (opposite of lively).

On Noise Levels and Dynamic range graph, I added measurements of Apple iPad and a reference sound card for comparison puposes.

What we see here is good performance. In theory and measured in ideal conditions Galaxy S II has low noise levels and very good dynamic range. However, if noise levels are remarkably low on high frequencies, they increase on lower frequencies which is not something expected nor a good sign as those are more likely to be heard.

What IMD + Noise means needs an explanation: I believe it’s safe to describe it as “all kind of noise and distortions happening when you play a signal” − at the opposite of the signal itself.

IMD + Noise importance is often underrated, like it was useless as we already have another distortion value (THD). Still, it’s often more representative of the general performance and of the sound quality perceived.

No matter how low is the theoretical noise floor, Yamaha MC-1N2 DAC has issue when playing signals. As you can guess by this latest comparison graph and the number of spikes indicating some sound that shouldn't be there. iPad DAC is not perfect either, still it provides a much cleaner sound. The reference DAC shows how the graph should be.

-63.7dB level for “noise and distortions” is far from the level of performance expected from a last-gen audio IC.

This test consist of a single sine played going from a very low frequency to 22kHz.

Actually, when playing something as simple as a single frequency at one time result is not so bad; music is rarely made of simples sines.

Stereo Crosstalk.dB: -82.3

My guess is that Yamaha’s codec internal behavior is perturbed by a jittery clock source (being Exynos AP PLL clock). If not? it would mean the DAC design is flawed. The first hypothesis is more likely: implementation on small very low power board is always tricky.

You cannot avoid the distortions described here by using an external amplifier or any other equipment.

Exploring sound with spectrograms

A spectrogram lets you “see” the sound, why I’ll use this colorful presentation to show you some examples of Galaxy S II audio output.

Udial

udial is a very interesting sample circulating in forums for more than ten years. I didn’t manage to find its author to thank him for his clever idea. udial is a very efficient stress test that enables an easy test for clipping, re-sampling and some types of jitter.

Galaxy S II performance is not terrible but not good either. Artifacts are audible and can be seen in this spectrogram. I must admit some are a mystery to me like the “delayed” ones.

DNG analyzes the signal played and quickly shut down parts of the codec. It helps reducing the perceived hiss and reducing power consumption a little.

Eventually (after about 2 seconds of nothing played) the entire audio hardware is shut down by Android OS but the best part is that Digital Noise Gate feature is extremely efficient as anti-pop.

MC-1N2 performance is class leading on this regard.

Headphone amp

Galaxy S II built-in headphone amp is able to drive in-ears or full size cans to satisfying levels. I know for sure mobile devices are never LOUD enough. Samsung’s flagship is louder than iPhones, iPads, a first-gen Galaxy S.

This part may become a dedicated article but here are some facts already:

Remember isolating headphones are recommended when in loud environments rather than pumping volume too high and damage your hearing.

To me the quality of the amp itself is average-to-okay. Its hard to speak much about it as it’s most of the time amplifying the signal sent by a flawed DAC.

As distortion amount rises at highest levels, its probably MC-1N2 amp power stage implementation on Galaxy S II board does not have much headroom. More measurements may be welcome here.

High output impedance

One characteristic of Galaxy S II's headphone driver is its relatively high impedance: higher than competitor chips. Power efficiency diminishes when the output impedance grow: energy lost in heat. This is why Yamaha’s choice of design is surprising.

I measured mine at 49 Ω.

A notable side effect of this characteristic is that the headphone output becomes less loud with low impedance cans.

Output impedance doesn’t have much effect on 300 Ω gear, but on common 16 Ω earphones:

Gain is lowered, hiss level is reduced: nice bonus

Frequency response shift: less bass, more highs. Okay if the tiny speakers was too bassy, terrible if the headphones were bright already.

As a result, Galaxy S II might play well with some equipment but also reveal the worst side of other with harsh and aggressive rendering.

This output impedance is why opinions about Galaxy S II audio are so contradictory in forums: experience can vastly differ depending on your choice of headphones.

Appreciation note

There are many issues or flaws listed and demonstrated in this article. However it doesn’t mean Galaxy S II is unable to play music.

Compared to the average Android phone it probably sounds better already. Explanations mean to show where there’s headroom for improvement on the next devices.

We're more than willing to discuss audio testing methodology with manufacturers to help improve the next generation of phones.

Samsung Music Player

Samsung updated their Google music player replacement look and feel with TouchWiz 4.0.

It still supports FLAC natively, which is a nifty feature for audiophiles and its simple interface and efficient will satisfy most users.

This pre-installed music player still lacks a much desired gapless feature, which means listening to mixes, concerts records or classical music won’t be as pleasing as it should.

You’ll find an 8 band graphic EQ in settings as well as EQ presets and additional sound effects adding reverberation, spatialization or stereo enhancements. Some effects are interesting if you’re not looking especially for an hi-fi accurate sound reproduction. However I would suggest to stay away of the EQ presets as much as possible:

If you really need to use this EQ, one workaround in using the graphic EQ manually instead: only attenuate but never increase some frequencies, those you find too present. This is in general the best way to use an EQ and find a more balanced sound response to correct headphone or speaker response.

132 Comments

Staggering review, you really are the most comprehensive and scientific reviewer around, bravo!

Samsung have really impressed with this phone, in terms of how much effort they have invested in the hardware and software. One thing still stands out for me, the battery life. While good, it still doesn't hold a candle to the iPhone 4, as shown on the charts.Reply

What do you mean?Its about 30% worse when web browsing (mostly because of the much larger screen I reckon), but better in the other tests.

If you are one of those old timers who actually use the phone for talking the SGSII is about 30 better ;)When I am low on battery, and don't have access to a charger, that's usually what I would prioritize. Reply

Alot of people that have the Samsung Galaxy S2 are suffering from framerate problems when using either 720p or 1080p in low light including myself.

What basically happens is when the camera tries to focus in lowlight the framerates drop to around 13fps, then jump back upto around 30fps again, basically making any HD video recording useless in low light because of the stuttering, the only fix that is known is to drop the exposure to -2 as this stop the stuttering, or use 480p when indoors or poor light.

Some folks have returned their SGS2 because of this problem, only to receive another with the same problem.

There has been a couple of camera firmware updates on Samung own app site, which to this date still hasn't sorted the problem out & in some cases people that weren't suffering from this problem, now have it after updating the camera firmware.

Can any of you guys at Anandtech test your SGS2 in low light with either 720p or 1080p to see if the mobile you received for reviewing also suffer from this problem.

But what is strange is that not everbody has the framerate problem, so it could be due to which sensor you get with your SGS2, and could proberly be sorted with a firmware update eventually.

Anyways people with this problem and there is a few can be found in this post over at XDA

Hi, i have exactly the same problem with my samsung galaxy s2.I got casual stuttering (a frame loss) during normal light conditions and severe stuttering under low light conditions.As soon as the firmware raises the sensor gain to match the detected light, the framerate goes down to 25fps and when autofocus occours the framerate goes down to 13fps, and then returns back to 25fps when the autofocus is finished.I olso noticed that when i try to frame a tv or a monitor, severe banding occours. Even taking a video when the light source is a tv or a monitor, banding occours. Seems like the isp isn't able to compensate the frequency of the light source.In a lot of situations it's impossible to take a video due to the severe stuttering :(Any one of you has these problems? How to solve it?

I would like to ask to the autor:did you notice some problem with the display? There is a thread in the xda-developers forum that speaks about the yellow tinting or faded out left side of the screen. Please can you report about this problem?Reply

Why dont you just admit it's the best phone around hands down? :) Not just the best Android phone. It's clearly miles superior to the outdated iPhone 4.

Shame you yanks have had to wait forever to get it, only to get 3 different versions that dont even look as good and have ridiculous names. I've been using a GSII since April and it's just unmatched.Reply